CN110906364A

CN110906364A - Metal insulating brick for a combustion chamber of a gas turbine

Info

Publication number: CN110906364A
Application number: CN201910863143.8A
Authority: CN
Inventors: V.多利亚诺; D.利卡塔; V.皮斯通
Original assignee: Ansaldo Energia SpA
Current assignee: Ansaldo Energia SpA
Priority date: 2018-09-14
Filing date: 2019-09-12
Publication date: 2020-03-24
Anticipated expiration: 2039-09-12
Also published as: CN110906364B; EP3623703A1; EP3623703B1; RU2019128442A

Abstract

A metal insulating brick for a combustor of a gas turbine engine includes a shield plate having a first face, a second face opposite the hot face, and a trailing edge. The outer rim extends from the shield plate in a direction opposite the first face and has sides and a rear. The first face of the shield plate is configured as a portion of a surface of revolution about the central axis. A seal bore is disposed in the outer rim and includes a side seal bore in the side portion and a rear seal bore in the rear portion. Each side seal bore has a respective side bore axis that forms a first angle of ± 15 ° with a first reference plane. The projection of the respective lateral hole axis on the first reference plane forms a second angle of ± 30 ° with a second reference plane perpendicular to the central axis. The first reference plane is parallel to the central axis and perpendicular to a mid-plane of the first face of the shield plate including the central axis.

Description

Metal insulating brick for a combustion chamber of a gas turbine

Cross Reference to Related Applications

This patent application claims priority to european patent application No. 18425075.1 filed on 9, 14, 2018, the entire disclosure of which is incorporated herein by reference.

Technical Field

The present invention relates to a metal insulating brick for a combustion chamber of a gas turbine.

Background

It is known that, due to the high temperatures generated during the operation of the machine, the combustion chamber of a gas turbine must be provided on the inside with a heat-insulating lining made of refractory material. The thermal liner is generally formed from a plurality of refractory bricks arranged in successive rows on an inner wall of the combustor casing so as to define a substantially continuous surface. In an annular type combustion chamber, the refractory bricks are arranged circumferentially around the rotor axis.

In particular in annular combustors, the assembly of the refractory bricks involves the insertion and sliding of the connecting elements along the circumferential guides.

In general, in practice, the refractory bricks have grooves on opposite sides and are fixed to the shell by means of connecting elements which are coupled to ribs defined by the grooves. In principle, the connecting element for one side of the refractory brick is inserted into a guide on the shell and is slid into the corresponding fastening position. The refractory bricks are then arranged in the seats with the sides engaging the fastening elements. Additional connecting elements are inserted along the guides and made to slide to couple with the sides of the tile which are still free.

Therefore, special measures are required for the last brick of each row.

According to a known solution, in each row a metal brick is used, which has through holes and is fixed to the casing by means of micro-cast screws inserted from the outside and engaged on a set of pre-assembled springs. In this way, it is not necessary to slide the fastening element and the assembly can be used in a relatively easy manner. Metal bricks have a lower resistance to thermal stresses than refractory bricks and require special cooling systems. This is typically accomplished by extracting a cooling flow of relatively fresh air from an intermediate stage of the gas turbine compressor and by directing the cooling flow toward the component under thermally critical conditions.

The cooling flow does not directly participate in the power generation and therefore affects the efficiency of the gas turbine engine. It is of general interest to reduce the air consumption for cooling purposes, which is not to a satisfactory extent in the currently available metal insulation blocks. This applies in particular to the most downstream row of insulating bricks, which are generally made entirely of metal and are configured to be coupled to the inlet of the expansion section of the gas turbine engine. In fact, the interface region of the combustion chamber and the expansion section is subjected to hot gas ingestion even more than other parts of the heat shield of the combustion chamber of the gas turbine.

Disclosure of Invention

It is therefore an object of the present invention to provide a metal insulating brick for a combustor of a gas turbine heat brick module (heat tilesmodule) and a gas turbine combustor, which allow to overcome said limitations.

According to the present invention, there is provided a metal insulating brick for a combustion chamber of a gas turbine engine, the insulating brick comprising:

a shield plate having a first face which, in use, is exposed to hot gas flowing through a combustion chamber of a gas turbine engine, a second face opposite the first face, and a trailing edge;

an outer rim extending from the shield plate in a direction opposite to the first face thereof and having a first side and a second side opposite to the first side;

a rear surface and a rear edge between the first face and the rear surface of the shield plate;

a plurality of sealing apertures in the outer rim;

wherein:

the first face of the shield plate is configured as a portion of a surface of rotation about the central axis;

the seal bores include a plurality of side seal bores in the first and second sides of the outer rim and a plurality of back seal bores in the back of the outer rim, each side seal bore having a respective side bore axis and each back seal bore having a respective back bore axis;

for each side seal bore, the respective side bore axis forms a first angle of ± 15 ° with a first reference plane, and a projection of the respective side bore axis on the first reference plane forms a second angle of ± 30 ° with a second reference plane perpendicular to the central axis;

the first reference plane is parallel to the central axis and perpendicular to a mid-plane of the first face of the shield plate including the central axis.

The sealing effect achieved thereby is very effective in preventing hot gas ingestion between adjacent bricks, and in particular on the sides of the bricks. Due to the effectiveness of transferring and exhausting hot gases, the insulating brick needs to reduce sealing gas flow and help improve the efficiency and performance of the gas turbine engine.

According to one aspect of the invention, the side sealing apertures have a respective diameter of between 1mm and 5 mm.

According to one aspect of the invention, the first angle of the side seal bore in one of the first and second sides of the rim is between 0 ° and 15 °, and the first angle of the side seal bore in the other of the first and second sides of the rim is between 0 ° and-15 °.

It is thus possible to make it possible to further improve the sealing effect.

According to an aspect of the present invention, the pair of respective side seal holes provided in the first side portion and the second side portion, respectively, are arranged such that the outlets thereof are located at respective positions in a direction parallel to the central axis.

In this way, the relative inclination and the corresponding axial position of the side sealing holes provide an opposite sealing action in the gap between two adjacent bricks and respectively simultaneously make the sealing action effective.

According to one aspect of the invention, for each back seal bore, the respective back bore axis forms a third angle between 5 ° and 45 ° with a direction parallel to the central axis.

The configuration of the aft seal bore is particularly effective in preventing hot gas ingestion in the gap downstream of the brick, such as at the interface between the combustor and the inlet of the expansion section of the gas turbine engine.

According to one aspect of the invention, the second face and the outer rim define a recess, and the respective rear bore axes of the rear seal bores are inclined such that fluid flowing from the recess to the outside through the rear seal bores is directed towards the central axis.

According to one aspect of the invention, the rear sealing aperture has a corresponding diameter of between 1mm and 5 mm.

According to one aspect of the invention, the trailing edge is rounded with a first radius of curvature, preferably between 1mm and 3 mm.

According to one aspect of the invention, the rear surface of the insulating block 18 has a first recessed area and a second recessed area separated by a ridge, all extending parallel to the rear edge between the first and second sides of the outer rim.

According to one aspect of the invention, the first concave area is delimited by the trailing edge and the ridge and has a second radius of curvature, preferably between 20mm and 30 mm.

According to one aspect of the invention, the first and second sides of the outer rim have respective lateral projections and recesses alternating in a direction parallel to the central axis, the lateral projections and recesses being configured such that when the insulating brick and another identical insulating brick are arranged side by side, the alternating lateral projections and recesses of the insulating brick engage with the alternating lateral projections and recesses of another insulating brick.

The lateral projections and recesses in the sides of the outer rim further improve the sealing action simultaneously by forming labyrinth gaps between adjacent bricks.

According to one aspect of the invention, a gas turbine engine comprises an annular combustion chamber provided with a heat shield, wherein the heat shield comprises at least one heat insulating brick according to the above definition, and the combustion chamber extends around a central axis.

According to one aspect of the invention, a gas turbine engine comprises an expansion section having an inlet vane stage configured to receive hot gas flowing from a combustion chamber, wherein the heat shield comprises a plurality of heat insulating bricks as defined above arranged about a central axis to form an outlet row at an interface with the inlet vane stage of the expansion section.

According to one aspect of the invention, the outlet row of heat shields and the inlet vane stage of the expansion section are axially separated by an annular gap, the insulating brick has a respective trailing edge that projects axially towards the inlet vane stage of the expansion section, thereby partially closing the gap, and the aft seal bore faces the gap.

Due to the shape of the trailing edge of the insulating brick, the space required to shield against hot gas ingestion is reduced, particularly at the interface of the combustion chamber and the expansion section of the gas turbine engine. Thus, the need for sealing air is reduced.

According to one aspect of the invention, a gas turbine engine includes an air plenum surrounding a combustor, wherein the combustor includes a shell to which insulation bricks are secured, and wherein a cooling chamber is defined between the shell, a second face, and outer edges of the respective insulation bricks, the cooling chamber being fluidly coupled to the air plenum through a feed hole in the shell.

According to one aspect of the invention, a sealing layer is provided between the outer edge of each insulating tile and the casing of the combustion chamber, the sealing layer being defined, for example, by a ceramic matrix layer.

Drawings

The invention will now be described with reference to the accompanying drawings, which illustrate some non-limiting embodiments of the invention, and in which:

FIG. 1 is a cross-sectional side view of a gas turbine engine cut along a longitudinal axial plane;

FIG. 2 is an enlarged cross-sectional side view of the combustor of the gas turbine engine of FIG. 1, cut along a longitudinal axial plane;

FIG. 3 is an enlarged cross-sectional view of an interface of a combustor cut along a longitudinal axial plane and including insulation bricks and an expansion section of the gas turbine engine of FIG. 1 according to an embodiment of the invention;

figure 4 shows an enlarged detail of the interface of figure 3;

FIG. 5 is a rear (rear) view of the insulating brick of FIG. 3;

FIG. 6 is a bottom view of the insulating brick of FIG. 3, the visible part being oriented towards the outside of the burner;

FIG. 7 is a perspective view of the insulating brick of FIG. 3;

figure 8 is a perspective view of a detail of the casing of the burner of figure 2;

figure 9 schematically shows quantities related to the insulating brick of figure 3;

figure 10 shows a further enlarged detail of figure 4;

FIG. 11 is a bottom view of an insulating brick according to another embodiment of the invention; and

FIG. 12 is a side view of the insulating block of FIG. 11.

Detailed Description

Fig. 1 shows a gas turbine engine 1 of a power plant as a whole.

The gas turbine engine 1 comprises a casing 2 and a rotor 3 rotatably mounted in the casing 2. The shell 2 and the rotor 3 extend along a centre axis AC and form a compressor 4 and a turbine or expansion section 5. The combustor 7 is disposed between the compressor 4 and the expansion section 5 and includes an annular combustion chamber 8 and a plurality of burners 10, the annular combustion chamber 8 also extending about the central axis AC.

An air plenum 11 is provided around the combustor 7 for supplying air for combustion, cooling air and sealing air.

As shown in fig. 2, the combustion chamber 8 comprises an annular casing extending around a central axis AC and comprising a first radially outer casing 13 and a second radially inner casing 14. The combustion chamber 8 is provided with a heat shield 15, which heat shield 15 covers the surfaces of the first and

second shells

13, 14 that are exposed to hot gases in use, and comprises a plurality of refractory heat insulating bricks 17 and a plurality of metal heat insulating bricks 18. The refractory and metal heat-insulating

bricks

17 and 18 are all fixed to the first shell 13 or the second shell 14. The refractory insulation bricks 17 are arranged in a plurality of annular rows. The outlet row 20 (see also fig. 3) at the interface between the combustion chamber 8 and the expansion section 5 is formed by metal insulation bricks 18.

Fig. 3 and 4 illustrate in more detail the interface between the combustion chamber 8 and the inlet vane stage 21 of the expansion section 5 of the gas turbine engine 1, which inlet vane stage 21 is configured to receive the hot gas flowing out of the combustion chamber 8. In one embodiment, the outlet row 20 of metal insulation bricks 18 is separated from the inlet vane stage 21 by an annular gap 22.

One of the metal insulating tiles 18 is shown in fig. 5-7; it is understood that all other metal insulation bricks 18 of the outlet row 20 have the same structure.

The insulating block 18 comprises a shield plate 25 having a hot face 25a which is exposed, in use, to hot gases flowing through the combustion chamber 8 and a cold face 25b opposite the hot face 25 a. Furthermore, the insulating block 18 has an aft face 18a arranged downstream with respect to the hot gas flow direction and a trailing edge 18b between the hot face 25a and the aft face 18 a. A central hole 26 through the shield plate 25 allows the insertion of screws (not shown) for fixing the insulating brick 18 to the first shell 13 in a known manner. In addition to surface features such as the central hole 26, the hot face 25a of the shield plate 25 is configured substantially as a portion of a surface of revolution about a central axis that coincides with the central axis AC of the gas turbine engine 1 when the insulating brick 18 is assembled to the first casing 13. The insulating block 18 also comprises an outer rim 27, which rim 27 extends from the shielding plate 25 in the opposite direction to the hot face 25a and delimits, with the cold face 25b, a recess 28. The outer rim 27 has a first side 27a, a second side 27b opposite the first side 27a, and a rear portion 27c that at least partially defines the rear surface 18a of the insulating tile 18. Thus, a cooling chamber 29 is defined between the first shell 13, the cold side 25b and the outer rim 27 of each insulating tile 18. As shown in fig. 3 and 8, the cooling chamber 29 is fluidly coupled to the air plenum 11 through a feed hole 40 in the first shell 13. Furthermore, a sealing layer 50 is provided between the outer edge 27 of each insulating tile 18 and the first casing 13 of the combustion chamber 8. The sealing layer 50 may, for example, be defined by a ceramic matrix layer capable of withstanding temperatures up to at least 800 ℃, and may have the same profile as the outer rim 27, for example having a thickness of 0.5-1.5 mm.

A plurality of sealing holes are provided in the outer rim 27. Specifically, the seal apertures include a plurality of side seal apertures 30 in the first and

second sides

27a, 27b of the rim 27 and a plurality of rear seal apertures 31 in the rear portion 27c of the rim 27. The side seal holes 30 and the rear seal hole 31 define passages to supply seal air from the cooling chamber 29 to the outside around the insulating brick 18, i.e., the inlets of the side seal holes 30 and the rear seal hole 31 are in the cooling chamber 29.

The pairs of the respective side seal holes 30 provided in the first and

second side portions

27a and 27b, respectively, are arranged such that the outlets thereof are located at respective positions in a direction parallel to the central axis a. Thus, the outlets of the side sealing holes 30 of the adjacent insulation bricks 18 are disposed facing each other.

As also shown in FIG. 9, each side seal bore 30 has a respective side bore axis AS that forms a first angle α of + -15 deg. with a first reference plane P1. the first reference plane P1 is parallel to the central axis AC and perpendicular to a mid-plane PM. of the hot face 25a of the shield plate 25 including the central axis AC. the projection of the side bore axis AS onto the first reference plane P1 forms a second angle β of + -30 deg. with a second reference plane P2 perpendicular to the central axis AC. in one embodiment, the side seal bore 30 has a respective diameter of between 1mm and 5 mm. As understood herein, the first angle α is positive when the inlet of the side seal bore 30 is closer to the shield plate 25 than the outlet (FIG. 5, left side), and the second angle α is negative when the inlet of the side seal bore 30 is farther from the shield plate 25 than the outlet (FIG. 5, right side). the first angle α is negative when the inlet of the side seal bore 30 is closer to the rear 27c of the outer rim 27 (6, left side, 866, or second, positive angle, 866, respectively, left side, right side, and right side, β.

In one embodiment (FIG. 6), the side seal apertures 30 of the first side 27a of the outer rim 27 have an opposite inclination relative to the side seal apertures 30 of the second side 27 b. in other words, the first angle α of the side seal apertures 30 in one of the first and

second sides

27a, 27b of the outer rim 27 is between 0 and 15 and the first angle α of the side seal apertures 30 in the other of the first and

second sides

27a, 27b is between 0 and 15 or both between 0 and 15.

Second angle β of side seal bore 30 in one of first side 27a and second side 27b of outer rim 27 is between 0 ° and 30 °, and second angle β of side seal bore 30 in the other of first side 27a and second side 27b of outer rim 27 is between 0 ° and-30 °.

The side sealing holes 30 configured as described above are very effective in sealing spaces between adjacent bricks and thus prevent hot gas ingestion therethrough. In effect, the side sealing apertures 30 feed an oblique jet of sealing air into the space between adjacent bricks. The jets of sealing air interact and create a circulation that avoids the passage of hot gases from the combustion chamber 8 towards the first casing 13. Improved thermal protection and reduced air consumption is thus achieved.

The rear seal hole 31 is arranged to face the gap 22 (fig. 3 and 4), so that the seal air flowing out of the rear seal hole 31 from the recess 28 is supplied into the gap. Each rear seal bore 31 has a respective rear bore axis AA that forms a third angle γ between 5 ° and 45 ° with a direction parallel to the central axis AC. More specifically, the rear hole axis AA of the rear seal hole 31 is inclined such that the seal air flowing from the recess 28 to the outside through the rear seal hole 31 is directed toward the center axis AC. The rear sealing aperture 31 also has a corresponding diameter of between 1mm and 5 mm.

As shown in fig. 4, due to the inclination of the aft seal bore 31, the jet of seal air is directed across the gap 22, reaching the outer platform 37 of the inlet vane stage 21 and diverging towards the insulation brick 18, thus creating a vortex V in the gap 22 that prevents ingestion of hot gases that may approach the gap 22.

The trailing edge 18b of the insulating brick 18 projects axially towards the inlet vane stage 21 of the expansion section 5 and partially closes the gap 22. Further, the trailing edge 18b has a first radius of curvature R1 that is below the threshold radius, and is preferably between 1mm and 3 mm. Specifically, the radius of curvature R is sufficiently small to ensure that the gas HG flowing from the combustion chamber 8 separates from the insulating brick 18 at the trailing edge 18b, and to prevent hot gas HG from escaping into the gap 22 by the Coanda effect (Coanda effect) at least under base load operating conditions and preferably over a load range from a minimum ambient load to base load.

As shown in fig. 10, the rear surface 18a of the insulating block 18 has a first recessed area 18c and a second recessed area 18d separated by a ridge 18 e. The first 18c, second 18d and ridge 18e extend parallel to the trailing edge 18b between the first 27a and second 27b sides of the outer rim 27. The first recessed area 18c is bounded by the trailing edge 18b and the ridge 18e and has a second radius of curvature R2 of between 20mm and 30 mm. The second valley 18d area is bounded on one side by the ridge 18e and occupies the remainder of the rear surface 18a of the insulating tile 18. A plane tangential to the ridge 18e forms an angle δ of 35 ° to 45 ° with the axis of the central hole 26 of the shield plate 25 (see fig. 3).

The shape of the rear surface 18a of the insulating brick 18 helps to excite the vortices V and thus improves the sealing of the gap 22 against hot gas ingestion.

The rear surface 18a of the insulating block 18 and the hot side 25a of the shield plate 25 may be provided with a thermal barrier coating 55. A bond coat 56 may be provided to improve the adhesion of the thermal barrier coating 55.

Figures 11 and 12 show an embodiment of the insulating brick, here indicated by the numeral 118, having the same general structure as the insulating brick 18 of figures 3-8, except that the first side 127a and the second side 127b of the outer rim 127 have respective lateral projections 150 and recesses 151 alternating in a direction parallel to the central axis (not shown here). The lateral projections 150 and recesses 151 are configured such that when identical insulation bricks 118 are arranged side-by-side, alternating lateral projections 150 and recesses 151 of adjacent insulation bricks 118 engage each other. The shape of the sides of the insulating tiles 118 forms a labyrinth, which contributes to the sealing effect, thus further reducing the need for sealing air. To facilitate the mounting and coupling of adjacent insulation tiles 18, the lateral protrusions 150 and the side faces 152 of the recesses 151 form an angle epsilon of between 60 deg. and 90 deg. with a direction parallel to the central axis AC.

It is finally apparent that modifications and variations can be made to the insulating brick described and illustrated without departing from the scope of protection of the accompanying claims.

In particular, the use of insulation according to the invention is not limited to the last row at the outlet of the combustion chamber. It is conversely understood that the described insulating brick may be well used to form an intermediate row of heat shields upstream of the interface with the expansion section of the gas turbine engine. For example, a row of insulating bricks according to the invention may be provided adjacent to the last row. The last row in this case may be of any conventional type. Furthermore, the insulation blocks described may be used as closed blocks in any upstream row. Installation of the last brick in the row of heat shields typically requires special installation procedures and means. Special bricks are also usually required. Metal bricks are particularly suitable for this purpose, as they allow greater flexibility in manufacture (e.g. in shape). Thus, the insulating brick as described above may be used as a closing brick to improve efficiency and/or to provide more reliable protection against the adverse effects of hot gases.

Claims

1. A metal insulating brick for a combustion chamber of a gas turbine engine, the insulating brick comprising:

a shield plate (25) having a first face (25a) which is exposed, in use, to hot gas flowing through a combustion chamber (8) of a gas turbine engine (1), a second face (25b) opposite to the first face (25 a);

a rear surface (18a) and a rear edge (18b) between a first face (25a) of the shield plate (25) and the rear surface (18 a);

an outer rim (27) extending from the shield plate (25) in a direction opposite to the first face (25a) thereof and having a first side portion (27a), a second side portion (27b) opposite to the first side portion (27a), and a rear portion (27 c);

a plurality of sealing apertures (30,31) in the outer rim (27);

wherein:

the first face (25a) of the shield plate (25) is configured as a portion of a surface of rotation about a central Axis (AC);

said sealing apertures (30,31) comprising a plurality of side sealing apertures (30) in a first side (27a) and a second side (27b) of said outer rim (27) and a plurality of rear sealing apertures (31) in a rear portion (27c) of said outer rim (27), each side sealing aperture (30) having a respective side aperture Axis (AS) and each rear sealing aperture (31) having a respective rear Aperture Axis (AA);

for each side seal bore (30), the respective side bore Axis (AS) forms a first angle (α) of ± 15 ° with a first reference plane (P1), and a projection of the respective side bore Axis (AS) on the first reference plane (P1) forms a second angle (β) of ± 30 ° with a second reference plane (P2) perpendicular to the central Axis (AC);

the first reference plane (P1) is parallel to the central Axis (AC) and perpendicular to a median Plane (PM) of a first face (25a) of the shielding plate (25) comprising the central Axis (AC).

2. Insulation block according to claim 1, wherein the side sealing holes (30) have a respective diameter between 1mm and 5 mm.

3. Insulation brick according to claim 1, wherein the first angle (α) of the side sealing hole (30) in one of the first and second sides (27a, 27b) of the outer rim (27) is between 0 ° and 15 ° and the first angle (α) of the side sealing hole (30) in the other of the first and second sides (27a, 27b) of the outer rim (27) is between 0 ° and-15 °.

4. Insulation brick according to claim 1, wherein the second angle (β) of the side sealing hole (30) in one of the first side (27a) and the second side (27b) of the outer rim (27) is between 0 ° and 30 ° and the second angle (β) of the side sealing hole (30) in the other of the first side (27a) and the second side (27b) of the outer rim (27) is between 0 ° and-30 °.

5. Insulation brick according to claim 1, wherein the pairs of respective side sealing holes (30) provided in the first and second side portions (27a, 27b), respectively, are arranged such that their outlets are located at respective positions in a direction parallel to the central Axis (AC).

6. Insulation brick according to claim 1, wherein the rear hole axis (AA) of the rear sealing hole (31) forms a respective third angle (γ) of between 5 ° and 45 ° with a direction parallel to the central Axis (AC).

7. Insulating brick according to claim 6, wherein the second face (25b) and the outer rim (27) delimit a recess (29) and the respective rear hole axis (AA) of the rear sealing hole (31) is inclined so that the fluid flowing from the recess (29) to the outside through the rear sealing hole (31) is directed towards the central Axis (AC).

8. Insulation brick according to claim 6, wherein the rear sealing hole (31) has a respective diameter between 1mm and 5 mm.

9. Insulation block according to claim 1, wherein the rear edge (18b) is rounded, having a first radius of curvature (R1), the first radius of curvature (R1) preferably being between 1mm and 3 mm.

10. The insulating brick according to claim 9, wherein the rear face (18a) of the insulating brick 18 has a first recessed area (18c) and a second recessed area (18d) separated by a ridge (18e), all extending parallel to the rear edge (18b) between a first side (27a) and a second side (27b) of the outer rim (27).

11. Insulating brick according to claim 10, wherein the first concave area (18c) is delimited by the rear edge (18b) and the ridge (18e) and has a second radius of curvature (R2), the second radius of curvature (R2) preferably being between 20mm and 30 mm.

12. Insulation brick according to claim 1, wherein the first side (127a) and the second side (127b) of the outer rim (127) have respective lateral projections (150) and recesses (151) alternating in a direction parallel to the central Axis (AC), the lateral projections (150) and recesses (151) being configured such that the alternating lateral projections (150) and recesses (151) of the insulation brick engage with the alternating lateral projections (150) and recesses (151) of another identical insulation brick when the insulation brick and said another insulation brick are arranged side by side.

13. A gas turbine engine comprising an annular combustion chamber (8) provided with a heat shield (15), wherein the heat shield (15) comprises at least one heat insulating brick (18;118) according to any of the preceding claims, and the combustion chamber (8) extends around the centre Axis (AC).

14. The gas turbine engine of claim 13, comprising an expansion section (5), the expansion section (5) having an inlet vane stage (21) configured to receive hot gas flowing out of the combustion chamber (8), wherein the heat shield (15) comprises a plurality of insulating bricks according to any one of claims 1 to 12 arranged around the central Axis (AC) to form an outlet row at an interface with the inlet vane stage (21) of the expansion section.

15. The gas turbine engine according to claim 14, wherein the outlet row of heat shields (15) and the inlet vane stage (21) of the expansion section are axially separated by an annular gap (22), the trailing edge (18b) of the insulating brick (18) axially projects towards the inlet vane stage (21) of the expansion section, thereby partially closing the gap (22), and the aft seal hole (31) faces the gap (22).

16. The gas turbine engine of claim 12, wherein the trailing edge (18b) is rounded with a first radius of curvature (R1), the first radius of curvature (R1) being preferably between 1mm and 3mm, and wherein the first radius of curvature (R1) of the trailing edge (18b) of the insulating brick (18;118) is below a threshold radius, such that the first radius of curvature (R1) prevents deviation into the gap (22) by the coanda effect of Hot Gas (HG) flowing out of the combustion chamber (8) at least under base load operating conditions.